Siemens or Allen Bradley ?

Hi, will soon be evaluating our current manufacturer against Siemens and Allen Bradley, interested to hear peoples opinions before we get the sales\tech guys in to see us.

All our comms is ethernet. Important to us is Modbus TCP so they must be able to support this pretty much out of the box.

Our current software is IEC compliant so again this is a must as most of our DFB's are developed and set in stone.

We are looking for as little overhead as possible in our development of porting to a new platform.

Oh, we are on Schneider at the moment, M340, Premium and Quantum.

Looking forward to your thoughts, especially those that may be OEM's in UK\Europe but all input welcome.

Siemens S7 supports Modbus TCP. But each CPU that uses this protocol require a special license.
Dont think AB Logix supports Modbus TCP natively. But Prosoft makes a module that fits in a controllogix rack.

A comment: If the connectivity only goes upwards to the SCADA level, then I do not understand the requirement for Modbus TCP. Surely OPC is the way to go. If the connectivity is from device to device, then yes, Modbus TCP is probably the most widely supported protocol between many vendors.

Siemens IEC 61131-3 compliance is only partial.
SCL and GRAPH are compliant to IEC ST and SFC. The other languages STL, LAD and FBD, are not.
Rockwell RSlogix 5000 should be fully compliant with IEC61131-3.

tragically1969 said:

Hi, will soon be evaluating our current manufacturer against Siemens and Allen Bradley....

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Why ?

L D[AR2 said:

Why ?

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Too long and a delicate subject to go into on a public forum !!

JesperMP said:

A comment: If the connectivity only goes upwards to the SCADA level, then I do not understand the requirement for Modbus TCP. Surely OPC is the way to go. If the connectivity is from device to device, then yes, Modbus TCP is probably the most widely supported protocol between many vendors.

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Correct, 99% of our slaves are modbus RTU, we use a Modbus Serial to TCP gateway to interface to these slaves, on a network we can have upwards of 500 slaves, hence a good solid Modbus implementation is a must.

If you stay with ET 200m I/O, Siemens has a Modbus RTU serial card available.
I don't think that there are an AB native cards available, but I could be wrong.

In either case this should not be a limiting factor. It is very easy to use a Prosoft Technologies gateway. Have used them for a long time and they are rock solid.

I was handed exactly this task in 2005.

I was working for a UK division of a large US company. The site standard was Schneider (mostly Quantums) and after some issues over a period of time, was told to evaluate both Allen Bradley and Siemens to be the new standard. (Not just PLC's - all control gear)

I contacted the UK sales department of both of these companies, (not identifying the actual client at this point) inviting them to survey the factory and negotiate a discount structure.

Siemens were fast,professional and helpful throughout the whole process. I'm afraid to say Allen Bradley didn't return any of my calls, even after a some nudging.

We had lots of Modbus+ networking on site and used the ProSoft Modbus+/PROFIBUS gateways for interfacing between the two manufacturers systems. They are pretty easy to set up and have been very reliable.

Go back 7+ years and i would be saying AB, however i have converted and as much as step 7 isnt a logix product (prepare for taking flak) the siemens stuff from the ground up including support, sales product knowledge and the whole shooting match is far better (at least In My Opinion - and im biased to the uk )

504bloke said:

the siemens stuff from the ground up including support, sales product knowledge and the whole shooting match is far better

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Never thought I'd read this from you Dave

504bloke said:

......the siemens stuff from the ground up including support, sales product knowledge and the whole shooting match is far better......

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Too bad that's not true in my geographical location, there is definitely something lacking from the local sales people.

Surely B&R...

1 Tool for every automation component. Programming PLC with ANSI C and more..

thanks..

Agreeing with a previous poster, in the past (5 plus years ago) I would have said go with Allen-Bradley. Now having tried the Siemens S71200 software and having experienced its ease of use, I would have to opt for Siemens. Even here where I live in the US, their support seems a slight step above ABs.

I have heard that they are also going to upgrade the software for the S7-300 AND S7-400 to be similar to the S71200, which would make it much more user friendly.

i have no idea for uk but in Canada, Siemens give us a better service and supports and it is free....No anual service program sold. Never stop answering even if you stop buying for a while...etcThis is a great advantage.

I personaly prefer to program Siemens because i got less communication problemes and never experienced a program lost in a plc vs 2-3 times AB program lost after electric problems etc...(We wire both the same way)

Yes modbus TCP isn't built in any of them but now you buy a driver to use profinet port from any ET200 300/400 plc to run as a modbus tcp port instead of buying the modbuss tcp module.

Both brand can run a serial port as modbus RTU port and be converted with a special module to modbus tcp....(more stuff = more problems)

For S7-200 their is no direct connection for modbus tcp but this plc is on the way to phase out for the new S7-1200 with a built in ethernet port that will probably be compatible with modbus.....

In america i think it's better for service and support from Siemens to use their web service instead of trying to reach someone on the phone.

katratzi said:

I have heard that they are also going to upgrade the software for the S7-300 AND S7-400 to be similar to the S71200, which would make it much more user friendly.

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Actually S7-200 has is own soft (microwin without integration)vs all other 200s 300 and 400 using Step 7 integrating everything connected to the network and using the same database tags...

The S71200 is the evolution from the 200 and it is actually using a lite version of step 7 working only for the 1200.

Actually, you need 1 soft for s7-200, another one for the 1200 and another 1 for all others....

Like RS500 and 5000....With AB

The wish would be to get a soft working for all of them with a licence price according to the size of cpu used.....Siemens guys told me that our wish is on the way....i expect to get it during the next year....

AB and Siemens soft seem to me definitely easier with ladder programming than other plc soft i used so far including GE and Shneider but again is a personal evalution based on my taste and experience

krk said:

Never thought I'd read this from you Dave

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I am Converted